Flip-up ladder



FIG. 1 is a perspective view of a flip-up ladder;

FIG. 2 is a front view of the flip-up ladder shown in FIG. 1;

FIG. 3 is a rear view of the flip-up ladder shown in FIG. 1;

FIG. 4 is a right side view of the flip-up ladder shown in FIG. 1;

FIG. 5 is left side view of the flip-up ladder shown in FIG. 1; and,

FIG. 6 is a top view of the flip-up ladder shown in FIG. 1.

The broken lines shown in the figures are for the purpose of illustrating boundaries and form no part of the claimed design. 

CLAIM The ornamental design for a flip-up ladder, as shown and described. 